The present invention relates to alarm systems having multiple remote devices in communications with a receiver/control unit wherein the receiver/control unit comprises one or more antennas; and in particular to such alarm systems wherein the receiver sensitivity is modified to increase the dynamic range of the receiver.
Contemporary radio frequency (RF) wireless security systems, such as those utilizing the ADEMCO 4281 or 5881 receiver, often use receiver antenna diversity for improving reception by counteracting the negative effects of multipath signal fading. The information transmitted from remote devices, which typically describes the state of various sensors, such as smoke, motion, breaking glass, shock and vibration detectors; door, window and floor mat switches; etc, comes from many different locations. In order to receive signals from transmitters at the maximum range, signals from transmitters at close proximity often saturate the receiver.
It is therefore an object of the present invention to provide a low cost method and system for increasing the dynamic range of a fixed gain receiver/control unit.